I was surprised the first time I went, but just as Curra above, says, the store is too loud, the music is too loud, and the music isn't yours. Are there EQ's applied? It is a neat idea, but not a great way to really 'hear' the headphone you want to buy.
In Seoul, #Apple store (with the hash mark) sells lots of high end phones that you can at least plug in to your amp/DAP to test with your own music. I tis loud and ... ew... lots of ear wax on the high end Shure and Victor earphones, but it is cool.